Update & follow up after many years.
I was using this road bike converted to electric as my main bike and only ebike until 2020. Then I felt the need for wider tyres and purchased components to build "gravel"bike with 650b wheels.
I considered the e-assist that useful that I wanted to have similar on my new gravel bike as well and purchased AKM q75sx from aliexpress. I thought this would be identical to my old q75 apart that it is suitable for disc brake but found some differences (more about those later). I remember reading somewhere that the q-motors from BMS battery are actually copies of original AKM motors.
I was hoping the smaller wheels would give a slightly "lower gear ratio" and hence slightly better performance/efficiency on steep hills (although the bigger - 42mm then, 48 now- tyres makes almost the same outer ⌀ on 650b as 28mm on 700cc I had) but found out the AKM q75sx has a little higher rpm with same the voltage than my old q75. Both were sold to me as 201 rpm. Also I think the newer q75sx is even quieter than my older q75, almost completely silent.
This spring I wanted to take my (gravel) bike to aeroplane and hence needed to take all the electric stuff off. With normal wheel and w/o any e-stuff it felt nicely light and agile, so I decided i would ride it at least few months like that.
Few days ago I gave my older road bike motor+rim and the controller+display(the only ones I have) to my dad. He has been interested to get some help for uphills and is currently installing the e-stuff into his bike. I m curious to see how it comes.
Overall these small motors have definitely been worth the money and hassle for me. During these years my riding has been going even more to direction that I am using the motor only on uphills and otherwise pedalling by myself. And with my new bike am riding often also non paved roads and offroad. So if there would be something similar to these q motors but with bigger reduction rations (= lower rpm / voltage ) that would be even better for me.
I guess my fitness has seen small improvement during these years since I dont anymore feel that much of a need for the e-assist.
Anyway I think I will still buy new lsw-675 controller (gave the old to my dad) and once again put the electric stuff on. Maybe this time will finally get programmable / current limiting/controlling controller. I see Groetech in Germany is selling those.
